50 Part 1 · An Introduction P RINCIPLE 4: S TRIVE FOR E LEGANCE An elegant solution uses a minimum of resources to best accomplish a task. P RINCIPLE 5: C OMPLEXITY IS I NEVITABLE , C ONVOLUTION IS N OT Big systems are inevitably complicated, but there is never a reason to have a convoluted sys- tem. Convoluted systems are generally the result of poor design, planning, implementation, or documentation, all of which lead to an unsightly mess that no one can ever figure out. Every- one I've ever known who has created convoluted systems as a means of "job security" has been eventually fired when they were not able to fix the system--sooner or later even they couldn't decipher their own convolution. P RINCIPLE 6: L EAVE R OOM FOR U NANTICIPATED C HANGES The cost of a piece of cable is extremely low relative to the costs of engineering the cable and the labor involved in running and terminating the cable. Always run spare cables, order extra terminals, and buy spare parts. Do this even if you cannot imagine any possible way the sys- tem could need expansion--someone will soon figure that out for you. I've never heard any- one complain that spares were in place, but I have heard plenty of complaints about not having expansion capacity. While it's often difficult to convince bean-counters, it's much cheaper to put in room for expansion now rather than later. P RINCIPLE 7: E NSURE S ECURITY These days, with so much literally "riding on" our systems, we have to make sure that our sys- tems are secure. Security applies to all types of devices in a control system, but especially, of course, to computers and networks. Following is a basic list that I use for any computer-based, networked control system (which is just about all of them these days). Keep Your Show Network Off the Internet It's generally a lot tougher for a malicious hacker to get into your network if it's not connected to the Internet. If you need to connect your network to the Internet for a software update (and your IP address scheme can accommodate it--see "Internet Protocol (IP)," on page 180) be